What Role Can Biofuels Play in Reducing Greenhouse Gas Emissions?
The shift from fossil fuels to renewable energy is occurring mainly at the power plant level. But what about transportation? Can we significantly reduce greenhouse gas emissions by switching to cleaner fuels? Or is this just an attempt to keep 20th century technology chugging along while trading one set of environmental problems for another?
Biofuels aren't new and they aren't used solely for transportation. Power plants can burn wood, for example and many of the first autos, including Ford's Model T, ran on ethanol or peanut oil. But they're now seen as an alternative to fossil fuels for transportation.
Biofuels can play an important role in reducing greenhouse gas emissions, especially for applications like long-haul trucking and possibly air travel.
Biofuels offer several advantages over fossil fuels. Most are less toxic. Crops used to produce them can be grown quickly, so unlike coal, oil and gas that take millions of years to form, they're considered renewable. They can also be grown almost anywhere, reducing the need for infrastructure like pipelines and oil tankers and, in many areas, conflicts around scarcity and political upheaval.
The main biofuels are ethanol and biodiesel. Biomass like wood can also be burned directly for fuel, although that usually produces more greenhouse gas emissions to produce the same amount of energy as burning fossil fuels. Biofuel greenhouse gas emissions are offset to a great extent because plants absorb and store carbon dioxide while they're growing and sometimes in roots left in the ground, so CO2 emissions are roughly equal to or less than what the crops store.
Despite the advantages, numerous problems have led many to question whether biofuels are a green alternative. Andrew Steer and Craig Hanson of the World Resources Institute noted in the Guardian that biofuel has three major strikes against it: "It uses land needed for food production and carbon storage, it requires large areas to generate just a small amount of fuel and it won't typically cut greenhouse gas emissions."
Producing biofuel with crops like corn often requires converting land from food to fuel production or destroying natural ecosystems that provide valuable services, including carbon sequestration. Crops also require fertilizers, pesticides and large amounts of water, as well as machinery for planting, growing, harvesting, transporting and processing. If forests are cleared for fuel crops and if the entire lifecycle of the fuels is taken into account, biofuels don't always reduce overall greenhouse gas emissions. Palm oil, used for biodiesel, is especially bad, because valuable carbon sinks like peat bogs and rain forests are often destroyed to grow palms.
Using better farming methods and more efficient feedstocks and growing fuel crops on land that isn't good for growing food can reduce land use and climate impacts. For example, fast-growing grasses, agricultural and forest-industry wastes and even household wastes can be used rather than crops like corn that are normally considered food. Some feedstocks are more efficient at producing energy than others. Ethanol from canola and sugarcane is better than from corn, as it delivers more energy compared to what's required to produce the fuel.
Cellulosic materials, including switchgrass and agricultural and forestry wastes, are even more efficient than sugar- and starch-based fuel stocks. They produce fewer greenhouse gases and don't normally displace food crops, but the process of converting cellulose to ethanol is more difficult than turning starch and sugars from corn or sugarcane to fuel. Some studies show switchgrass ethanol can produce 540 percent more energy than that required to produce the fuel, compared to just 25 percent more for corn-based ethanol. Experimental biofuels made from biomass like algae, as well as genetically synthesized organisms, show a great deal of promise, as they're efficient and can be produced without large land bases.
Biofuels can play an important role in reducing greenhouse gas emissions, especially for applications like long-haul trucking and possibly air travel. Biodiesel and gasoline mixed with ethanol are already widely available. Research into new types of biofuels is also important, but the massive amounts of land, biomass and water required to produce conventional biofuels mean they aren't a panacea. We can get further in transportation by focusing on fuel efficiency and conservation, increased public transit and other alternatives to private automobiles and shifting to electric vehicles, especially as clean electricity sources become more widely available.
Gardening the Seas to Save the World's Corals
As ocean waters warm and acidify, corals across the globe are disappearing. Desperate to prevent the demise of these vital ecosystems, researchers have developed ways to "garden" corals, buying the oceans some much-needed time. University of Miami Rosenstiel School marine biologist Diego Lirman sat down with Josh Chamot of Nexus Media to describe the process and explain what's at stake. This interview has been edited for length and clarity.
What is killing coral?
I wish we had an easy, straightforward answer for what's killing corals. We know there are many, many different factors influencing coral abundance, diversity, distribution and health these days, but I think the specific answer varies based on where you are.
Temperatures play a major role at global scales, and then you have all of these other, more local factors like disease, physical impacts of storms, or ship groundings.
Researcher Stephanie Schopmeyer prepares to out-plant Staghorn coral onto a Miami reef. Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science
We had the dredging of the Port of Miami channel a couple of years ago and that caused a lot of localized mortality due to sediment burial and sediment stress. You also have land-based sources of pollution that can damage by location and nutrient influence that causes algal overgrowth of corals.
Local factors are superimposed on regional factors directly related to global climate change. Changes in temperature, more temperature extremes, acidification of the water, changes in storm frequency and sea level rise— all are at different scales — but they all combine to cause coral mortality.
Factors vary both spatially and temporally, but the outcomes are all the same. Regardless of where you are, we've lost a tremendous amount of coral.
Nursery-raised Staghorn coral out-planted onto a reef by a citizen scientist.
In the face of all those threats, can restoration work?
Historically, restoration was developed and used for acute disturbances. A ship runs aground, and so then there's a recovery, and funds are allocated to recovering the reef structure at a given location, and then corals are planted on top of that. But as global conditions decline for coral reefs, there's now a need to scale up. So, we're not just dealing with the localized impact—we're looking at species declining throughout their range.
We need other tools at larger scales, and that's where coral reef gardening has come into play, because it works at larger scales compared to just dumping cement and rebuilding reef structures, costly endeavors that recover just a very small footprint. We're growing and planting these organisms.
Do you worry about planted coral dominating the reefs?
Initially, these techniques were developed for fast-growing corals. The genus that we're focusing on, Acropora, is threatened, so these are very important reef-building species.
When abundant, they monopolize shallow environments. They form thickets, extensive areas of high-density colonies. That's the way they used to grow, until about three to four decades ago when they got wiped out by disease and other factors. The branching corals that we're working with grow between 10 and 15 cm per branch per year, so that's very fast growth.
Through recent advances in coral aquaculture, we're now also able to grow massive species, the ones that grow very slowly. Mote Marine Lab has developed microfragmentation techniques where they can cut coral colonies very, very small and make them grow very, very fast. Although we focused on branching corals initially, now most of the programs, especially here in Florida, are expanding onto other threatened species.
Citizen scientists plant coral. Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science
Can these efforts solve the problem, or are they a placeholder until climate stabilizes?
You hit the nail on the head. One of the early criticisms of reef restoration was the scale issue and spending a lot of resources working on a very small footprint.
We've dealt with that now, over the past 10 years we've expanded to the point where we're growing thousands and thousands of corals—we're planting thousands and thousands of corals—so that issue of scale is no longer a valid criticism.
The other major criticism is that, even though we're planting a lot of corals, we're planting them onto environments where the same stressors that caused their initial mortality are in place. Now there is ocean acidification and increased temperatures, so things have gotten, in some cases, progressively worse.
Staghorn corals create a sustainable source of corals for use in restoration. Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science
That is a valid concern if we were just planting corals, but we're not just doing that. We're still concentrating on all of the other aspects of reef restoration, setting up marine protected areas to protect fish stocks and coral impacts, working to curb land-based sources of pollution, and setting up sedimentation and nutrient controls. And then, on a much larger scale, we're all trying to curb carbon emissions, trying to limit the greenhouse impacts and acidification impacts. All these tools just help us buy time.
We're also doing a lot of genomics work to see how corals can increase their resilience. A colleague of mine here at the Rosenstiel School at University of Miami, Andrew Baker, is stress-hardening corals. He works on coral symbiosis, and he found that by applying a little bit of non-lethal stress, he can make corals shuffle their Zooxanthellae, which are the endosymbiotic microalgae that provide energy to the corals. In that process, they're able to uptake Zooxanthellae that are more thermally tolerant. So, through the forced shuffling of symbionts, you may be able to buy these corals one or two degrees of tolerance, so that they become more tolerant to bleaching in future years. That is cutting-edge science.
We're trying to actually find out what makes corals survive, and trying to beef up their defenses and their resilience over time. And that's because we have access to all these coral genotypes through the active propagation from coral gardening.
Reposted with permission from our media associate Nexus Media.
